Tracks and instruments

Each track must have an instrument assigned to it, in order to
be heard. By default the first 16 tracks are assigned to the
16 instruments of the first available MIDI device, and the
next 16 tracks are assigned to audio.

To change the instrument assignment for a track,
right-click on the track label: a pop-up menu will appear from
which you can select among all the available instruments.

An instrument can be understood as a single channel on a
MIDI device, or as a mono or stereo audio output or an audio
synth plugin. Tracks containing note data should be assigned
to MIDI or synth plugin instruments, and those containing
audio to audio instruments. You can assign more than one
track to the same instrument, in which case the multiple
tracks will produce sounds in the same way (MIDI tracks playing
panned to the left with a flute, or audio tracks playing with the same
volume levels, through the same stack of
plugins.)

You can change various properties of the instrument
associated with a track using the Instrument
Parameter Box. This is where, for example, you would
set a MIDI instrument to use a particular patch and so
produce a particular sound (piano, strings etc).